RFR: 8317720: RISC-V: Implement Adler32 intrinsic [v2]

[Fei Yang]

On Wed, 3 Apr 2024 16:02:22 GMT, ArsenyBochkarev <duke at openjdk.org> wrote:

>> Hello everyone! Please review this non-vectorized implementation of `_updateBytesAdler32` intrinsic. Reference implementation for AArch64 can be found [here](https://github.com/openjdk/jdk9/blob/master/hotspot/src/cpu/aarch64/vm/stubGenerator_aarch64.cpp#L3281).
>> 
>> ### Correctness checks
>> 
>> Test `test/hotspot/jtreg/compiler/intrinsics/zip/TestAdler32.java` is ok. All tier1 also passed.
>> 
>> ### Performance results on T-Head board
>> 
>> Enabled intrinsic:
>> 
>> | Benchmark                          |    (count) |  Mode |  Cnt  |   Score  |  Error |  Units |
>> | ------------------------------------- | ----------- | ------ | --------- | ------ | --------- | ---------- |
>> | Adler32.TestAdler32.testAdler32Update |      64 | thrpt  | 25 | 5522.693 | 23.387 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |     128 | thrpt |  25 | 3430.761 |  9.210 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |     256 | thrpt |  25 | 1962.888 |  5.323 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |     512 | thrpt  | 25 | 1050.938 |  0.144 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |    1024 | thrpt  | 25 |  549.227 |  0.375 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |    2048 | thrpt  | 25 |  280.829 |  0.170 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |    5012 | thrpt  | 25 |  116.333 |  0.057 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |    8192 | thrpt  | 25  |  71.392 |  0.060 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |   16384 | thrpt |  25  |  35.784 |  0.019 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update |   32768 | thrpt |  25  |  17.924 |  0.010 | ops/ms |
>> | Adler32.TestAdler32.testAdler32Update  |  65536 | thrpt |  25  |   8.940 |  0.003 | ops/ms |
>> 
>> Disabled intrinsic:
>> 
>> | Benchmark                          |    (count) |  Mode |  Cnt  |   Score  |  Error |  Units |
>> | ------------------------------------- | ----------- | ------ | --------- | ------ | --------- | ---------- |
>> |Adler32.TestAdler32.testAdler32Update|64|thrpt|25|655.633|5.845|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|128|thrpt|25|587.418|10.062|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|256|thrpt|25|546.675|11.598|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|512|thrpt|25|432.328|11.517|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|1024|thrpt|25|311.771|4.238|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|2048|thrpt|25|202.648|2.486|ops/ms|
>> |Adler32.TestAdler32.testAdler32Update|5012|thrpt|25...
>
> ArsenyBochkarev has updated the pull request incrementally with eight additional commits since the last revision:
> 
>  - Dispose of some unneeded instructions
>  - Move buf_end up
>  - Add missing instructions for accum function split
>  - Prettify labels and accum function
>  - Split accum function
>  - Eliminate L_nmax loop counter
>  - Move repeating code under function
>  - Add `enter` and `leave`

I witnessed performance regression on unmatched board when count > 2048.
JMH numbers:

Before:
Benchmark                      (count)   Mode  Cnt     Score    Error   Units
TestAdler32.testAdler32Update       64  thrpt   25  1050.761 ± 54.862  ops/ms
TestAdler32.testAdler32Update      128  thrpt   25   953.858 ± 42.102  ops/ms
TestAdler32.testAdler32Update      256  thrpt   25   821.011 ± 21.154  ops/ms
TestAdler32.testAdler32Update      512  thrpt   25   624.207 ± 19.724  ops/ms
TestAdler32.testAdler32Update     1024  thrpt   25   436.040 ±  5.875  ops/ms
TestAdler32.testAdler32Update     2048  thrpt   25   265.020 ±  3.058  ops/ms
TestAdler32.testAdler32Update     5012  thrpt   25   124.934 ±  0.799  ops/ms
TestAdler32.testAdler32Update     8192  thrpt   25    70.026 ±  0.243  ops/ms
TestAdler32.testAdler32Update    16384  thrpt   25    35.885 ±  0.055  ops/ms
TestAdler32.testAdler32Update    32768  thrpt   25    16.883 ±  0.027  ops/ms
TestAdler32.testAdler32Update    65536  thrpt   25     7.648 ±  0.006  ops/ms

After:
Benchmark                      (count)   Mode  Cnt     Score    Error   Units
TestAdler32.testAdler32Update       64  thrpt   25  4360.280 ± 39.921  ops/ms
TestAdler32.testAdler32Update      128  thrpt   25  2766.595 ± 16.027  ops/ms
TestAdler32.testAdler32Update      256  thrpt   25  1634.373 ±  5.412  ops/ms
TestAdler32.testAdler32Update      512  thrpt   25   880.028 ±  1.463  ops/ms
TestAdler32.testAdler32Update     1024  thrpt   25   457.724 ±  0.296  ops/ms
TestAdler32.testAdler32Update     2048  thrpt   25   233.605 ±  0.072  ops/ms
TestAdler32.testAdler32Update     5012  thrpt   25    96.610 ±  0.020  ops/ms
TestAdler32.testAdler32Update     8192  thrpt   25    59.275 ±  0.012  ops/ms
TestAdler32.testAdler32Update    16384  thrpt   25    29.726 ±  0.004  ops/ms
TestAdler32.testAdler32Update    32768  thrpt   25    14.736 ±  0.009  ops/ms
TestAdler32.testAdler32Update    65536  thrpt   25     6.658 ±  0.002  ops/ms

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18382#issuecomment-2040891223